JPS6212829Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is an intake and exhaust control for a turbocharged diesel engine that aims to improve fuel efficiency at low and medium loads and improve transient response when the load increases. Regarding equipment.

[Prior art]

Some vehicles equipped with an internal combustion engine are equipped with a turbocharger that uses a turbine to recover thermal energy from exhaust gas and sends compressed air to the combustion chamber using a compressor connected to the turbine to increase engine power. It has been adopted.

[Problem that the invention attempts to solve]

By the way, when comparing non-supercharging and supercharging in engines of the same displacement, the fuel cost characteristics of turbocharging are good on the high load side, but tend to be poor on the partial load side. This is because, in the medium and low speed range, (i) pumping loss increases due to increased exhaust pressure due to turbocharger installation, and (ii) compression work increases due to increased intake pressure. , these act in the direction of increasing engine friction loss.

As described above, the conventional turbocharger was operated even when the engine was under low or medium load when it did not necessarily need to be operated, so there was a problem that the fuel efficiency was worse than when there was no supercharging. There was also a problem with transient response when the engine load increases, such as during acceleration.

The purpose of the present invention is to provide an intake/exhaust control device for a diesel engine with a turbocharger, which improves fuel efficiency at low and medium loads of the engine, and improves transient response when the engine load increases, such as during acceleration. It is in.

[Means for solving problems]

In order to achieve the above object, the present invention provides an intake/exhaust control device for a diesel engine with a turbocharger, in which thermal energy in exhaust gas of the engine is recovered by a turbine to drive a compressor.
In a diesel engine equipped with a turbocharger that sends intake air compressed by the compressor to a combustion chamber of the engine, a first passage installed to be able to bypass the compressor and a second passage installed to be able to bypass the turbine. a first switching valve that closes the first passage only when the engine is under high load; a second switching valve that closes the second passage only when the engine is under high load;
The two accelerator switches with different opening degrees, which are turned on sequentially as the engine load increases, the second switching valve and the first switching valve, are turned on by the two-step on operation of these accelerator switches. As the load increases, the second passage is closed and then the first passage is closed.
and a valve control mechanism that sequentially operates to close the passages.

[Effect]

With this configuration, when the engine is at low or medium load, the exhaust flow bypasses the turbine and the intake flow bypasses the compressor, so that the exhaust pressure and suction pressure are null when the supercharged engine is at low or medium load. It is maintained at the same level as supercharging. Also, when the engine load increases, such as during acceleration, the load is detected in two stages,
Based on this, the switching valve is also controlled in two stages to improve transient response. That is, as the engine load increases, the second switching valve first closes and all of the exhaust gas is supplied to the turbine, and if the load further increases in this state, the first switching valve closes. The boost pressure increases rapidly, improving transient response.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention.

A turbocharger 2 mounted on a diesel engine 1 is comprised of a turbine 3 driven by engine exhaust gas and a compressor 4 that feeds intake air into a chamber with supercharged air when the engine 1 is under high load. Air is introduced into the compressor 4 from an air cleaner 5 through a passage D, and supercharged air is sent into the engine 1 through a passage B. In addition, the passage B and the air cleaner 5 can bypass the compressor 4.
A passage A is disposed between them, and a switching valve 6 is provided within the passage A to close the passage at a predetermined time. The exhaust manifold of the engine 1 and the turbine 3 are connected by passages E and F, and a passage H is connected to the turbine 3 for exhaust gas. Passage H
Passage I leading to the muffler is connected to the
A passage G is connected between the connecting portion of both passages and the connecting portion of passages E and F, and a switching valve 7 is provided within the passage G.

In the above configuration, the switching valve 6 is at the broken line position when the engine 1 is under low or medium load, and is at the solid line position when the engine 1 is under high load. In addition, the switching valve 7 is located at the dashed line position when the engine is under low or medium load, is at the solid line position when the supercharging pressure in the passage C is below a predetermined value at high load, and is at the solid line position when the boost pressure in the passage C is below the predetermined value. between positions. Therefore, when the engine is under low or medium load, passages A and G are open, and on the compressor side, intake air is sent to engine 1 via passage A and passages D to B, and the pressure in passage C is close to atmospheric pressure. is maintained. In addition, since the passage G is open, almost no exhaust gas flows into the turbine 3, and the pressure in the passage E is kept low, but the compressor 4
Since the turbine 3 performs almost no compression work (because the switching valve 6 is open), the turbine 3 itself is kept at a high rotation speed because it is in an unloaded state.

When the engine is under high load and the pressure in passage C (supercharging pressure) is below a predetermined value, passages A and G are closed, all of the intake air passes through compressor 4, and all of the exhaust gas is transferred to the turbine. 3, the turbocharger is fully functional and operates like a normal turbo engine.

When the engine is under high load and the pressure in passage C (supercharging pressure) is equal to or higher than a predetermined value, passage A remains fully closed and passage G is slightly opened, so that the supercharging pressure is kept constant.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

In this embodiment, the switching valve 6 in the embodiment shown in FIG. 1 is provided at the connection between passages B and C.
Since the other configurations are the same as shown in FIG. 1, explanations of the configuration and operation will be omitted. In this embodiment, all the intake air during low and medium loads passes through the passage A and does not pass through the compressor 4, and the effect is the same as that of the embodiment shown in FIG.

Next, the control mechanism for the switching valves 6 and 7 in the first and second embodiments will be explained with reference to FIG. 3.

FIG. 3 is a circuit diagram showing an embodiment of the control mechanism, which is controlled using two accelerator switches. The switching valve 6 is driven by a diaphragm 60, and the switching valve 7 is driven by a diaphragm 70. An electromagnetic coil 32 for controlling an electromagnetic valve 33 is connected to the battery 25 via an accelerator switch 31, and an electromagnetic coil 35 for controlling an electromagnetic valve 36 is connected via an accelerator switch 34. The negative pressure ports of the solenoid valves 33 and 36 are connected to the vacuum pump 22, and the load side port of the solenoid valve 33 is connected to the diaphragm chamber 71 of the diaphragm 70.
At the same time, the negative line side port of the solenoid valve 36 is connected to the diaphragm chamber 61 of the diaphragm 60. Further, the diaphragm 72 of the diaphragm 70 is connected to the passage B or C. The ON operation of the accelerator switch 31 is performed when the accelerator switch 3
It is set to turn on at a small opening compared to 4.

In the above configuration, when the engine load increases such as during acceleration, the accelerator switch 31 is first turned on, the solenoid valve 33 is switched, atmospheric air is applied instead of the negative pressure applied to the diaphragm 70, and the switching valve 7 is turned on. Changes from the open state (dashed line position) to the closed state (solid line position). As a result, the passage G is closed and all of the exhaust gas is supplied to the turbine 3. When the load increases further in this state, the accelerator switch 34 is turned on, the solenoid valve 36 is switched, atmospheric pressure is applied instead of the negative pressure applied to the diaphragm 60, and the switching valve 6 changes from the open state (dotted line position). Changes to the closed state (solid line position). Therefore,
As the passage A is closed and all of the intake air is sent to the compressor 4, the boost pressure increases rapidly. Therefore, according to this embodiment, the transient response can be improved. Furthermore, when the pressure (supercharging pressure) on the outlet side (passage B or C) of the compressor 4 is higher than a predetermined value, the diaphragm is pushed back due to the supercharging pressure applied to the diaphragm chamber 72, and the switching valve 7 is slightly opened. When opened, boost pressure is maintained at a predetermined value.

[Effect of idea]

According to the present invention, when the engine is under low or medium load, the exhaust flow bypasses the turbine and the intake flow bypasses the compressor. can be made to the same level as without a turbo, so friction loss can be made to be the same as without a turbo. As a result, the fuel efficiency of the turbo diesel engine at low and medium loads can be made comparable to that of a turbo diesel engine without a turbo. Furthermore, when the engine load increases, the load is detected in two stages, and based on this, the switching valves are controlled in two stages so that the second switching valve and the first switching valve are sequentially closed. Therefore, it is possible to improve the transient response when the engine load increases.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a second embodiment of the present invention, and FIG. 3 is a circuit diagram showing an example of the control mechanism according to the present invention. 1... Diesel engine, 2... Turbo charger, 3... Turbine, 4... Compressor,
6, 7...Switching valve, 22...Vacuum pump,
25... Battery, 31, 34... Accelerator switch, 32, 35... Electromagnetic coil, 33, 36...
...Solenoid valve, 60,70...Diaphragm, A,
B, C, DEFG, H, I...Aisle.

Claims (1)

[Scope of utility model registration request] In a diesel engine equipped with a turbocharger that recovers thermal energy in engine exhaust gas using a turbine to drive a compressor and sends intake air compressed by the compressor to the combustion chamber of the engine, the compressor is installed so that it can be bypassed. a first passage installed to bypass the turbine; a first switching valve that closes the first passage only when the engine is under high load; a second switching valve that closes the second passage only when the engine load increases; two accelerator switches with different opening degrees that are turned on sequentially as the engine load increases; and a valve control mechanism that sequentially operates the switching valves so as to close the second passage and then close the first passage as the engine load increases by two-stage ON operation of these accelerator switches. Intake and exhaust control device for diesel engine with turbocharger.